John Carlson and Ruth Berg were both longtime employees at the private Christian school in Minneapolis when they were killed Wednesday in an explosion on campus. Their bodies were pulled from the rubble of a partially collapsed building after the blast, which investigators believe was sparked by a natural gas explosion.

Berg, 47, had been scheduled to be fitted for her wedding dress Thursday, her fiancé, Mark Burrington, told Minnesota Public Radio. The invitations for their September wedding arrived a day before the fatal explosion, which Burrington said he heard from his home just down the street.

He said he last spoke with Berg over the telephone Wednesday about having lunch together. A short time later, he heard the blast and ran to the scene.

“The first hallway I hit, there was a lot of like debris and stuff, and it literally looked like a bomb went off,” he said. “You turn the corner to go down to the office where she sits … As soon as I turned the corner, you could see the daylight, and I knew, you know, there’s something wrong.”

Berg worked for Minnehaha Academy for 17 years. On its Facebook page, the school said: “She welcomed everyone with a smile and was always willing to go the extra mile to help our students, families, and staff.”

Carlson graduated from the academy in 1953, and later sent his children to the school. He had been working there as a custodian for the past 14 years. He was also known for handing out ice cream bars to staff and students.

“He’d always talk to you in between classes and he would always offer you Dilly Bars,” student Roddy Macdonald told KMSP-TV. “He was super sweet and super friendly to everyone. He loved being here.”

The school said Carlson was its “biggest cheerleader.”

“He knew the students’ names. He was like a grandfather figure to them,” said Sara Jacobson, the school’s executive director for institutional advancement. “He loved people, he loved God and he loved his school.”